1. Field of the Invention
The present invention relates to chamber doctors and, more particularly, to a chamber doctor which is able to compensate for wear of a doctor blade.
2. Description of the Prior Art
Chamber doctors including doctor blades for wiping a cylinder to be inked are well known. The doctor blades are forced to contact the cylinder and thus are subject to wear. In order to increase the useful life of the chamber doctor the doctor blades must be readjusted to compensate for wear. A device which adjusts the working and closing doctor blades is described in German patent No. DE 42 13 660 A1. This patent discloses a chamber doctor having a working and closing doctor blade each displaceably disposed in a respective slot of the chamber doctor and pressed against the cylinder to be inked by springs to thereby readjust the doctor blades in accordance with wear on the blades. However, this device, due to the contract pressure forces and frictional forces between the tip of the doctor blade and the surface of the cylinder, applies a force vertical to the displacement direction of the doctor blade which results in frictional forces in the slot receiving the doctor blade thus inhibiting reliable readjustment of the doctor blade. Furthermore, due to its construction, ink is able to penetrate the slot receiving the doctor blade and accordingly reaches the large contact surface between the doctor blade and the blade holder causing the surface to become sticky when the ink dries. As a result of the dried ink frictional forces accumulate in an uneven manner having a negative influence on the contact pressure force of the doctor blade thus effecting the quality of wiping of the doctor blade.